Gas turbine engine

ABSTRACT

A recuperated gas turbine engine is disclosed, comprising: a heat exchanger, and gas turbine (including compressor, can-type combustor and turbine); wherein, said heat exchanger comprises a compressed air passageway and a turbine exhaust gas passageway adjacent to each other within the casing which extend spirally throughout said heat exchanger and towards an inner cylindrical chamber in which said combustor is positioned approximately to the center of said casing. Improved engine fuel efficiency is achieved by preheating the compressed air before it reaches the combustor with the higher-temperature exhaust gas. A can-type combustor is used for alleviating heat-dissipation issues to improve efficiency of the combustion. A concentric back-to-back rotor arrangement significantly shortens the length of a conventional engine turbine rotor which improves on the operational stability of a gas turbine engine.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to gas turbine engines and, moreparticularly, to a gas turbine engine capable of having compactdimensions, light weight, and improved fuel efficiency as well asproviding operational stability.

[0003] 2. Description of Related Art

[0004] Currently, a typical conventional gas turbine engine 9 generallycomprises a compressor section 91, a combustor section 92, and a turbinesection 93, wherein an engine core turbine rotor 95 having a shaft 950is positioned inside a casing 94, as shown in FIG. 1. An annular spaceis thereby formed between the shaft 950 and the casing 94 whichsubstantially encloses a conventional annular combustor 96 within.

[0005] Referring to FIG. 1, air is compressed after passing through aplurality of compressor stator blades 941 and compressor rotor blades981 to become highly pressurized gas due to centrifugal force anddiffusion effect. Compressed air then enters the annular combustor 96 tobe mixed with fuel for combustion which produces highly pressurized gasstream that is also high in temperature; the gas stream is then forcedout through a plurality of engine core turbine rotor blades 951 whichdrive the shaft 950 and the compressor rotor blades 981 into rotation.Subsequently, the gas stream passes through a plurality of turbine rotorblades 971 which drives a turbine rotor 97 into rotation to produceshaft power.

[0006] Nevertheless, an extra annular space is required inside thecasing 94 to accommodate the annular combustor 96 of the aforementionedconventional gas turbine engine 9 which not only makes compact enginedesigns difficult but also causes heat in the combustor to dissipatewithout performing any mechanical work.

[0007] After air is compressed as it enters the compressor section 91,it is fed directly into the annular combustor 96 to be combusted withfuel without any preheating. Due to the lack of preheating the air priorto combustion, extra fuel is needed inside the annular combustor 96,which decreases fuel efficiency of the conventional gas turbine engine9.

[0008] Furthermore, as shown in FIG. 1, the compressor rotor blades areformed on a compressor rotor 98 positioned in the front of the gasturbine engine 9 while the engine core turbine rotor 95 and the turbinerotor 97 are positioned in the rear. Any uneven vibration transmittedthrough the axis of the shaft 950 can cause unstable engine operation;especially when high operating temperature within the turbine section 93tends to shorten the operation life of different mechanical parts suchas a bearing.

[0009] Therefore, it is desirable to provide an improved gas turbineengine capable of having improved operational stability while at thesame time having the advantages of compact design, light weight, andenhanced fuel efficiency to mitigate and/or obviate the aforementionedproblems.

SUMMARY OF THE INVENTION

[0010] A primary object of the present invention is to provide a gasturbine engine which employs a Swiss-Roll type recuperator to improve onfuel consumption by using said recuperator as an energy-saving heatexchanger.

[0011] Another object of the present invention is to provide a gasturbine engine wherein a compressor rotor is concentrically positionedback-to-back with a turbine rotor on a single shaft to increaseoperational stability of said rotors.

[0012] Still another object of the present invention is to provide a gasturbine engine wherein a can-type combustor is used for alleviatingheat-dissipation issues to improve efficiency of the combustion.

[0013] The present invention achieves the above-mentioned objects byproviding a gas turbine engine comprising: a casing, a Swiss-Roll typerecuperator functioning as a heat exchanger, a combustor, and a turbineengine rotor comprising a coaxial compressor rotor and a turbine rotor;wherein, said casing takes an approximately cylindrical shape having acircular shoulder portion which extrudes outwardly and forms a casingopening to a first end and a bottom plate sealing a second end of saidcasing on the opposite side. Said Swiss-Roll type recuperatorfunctioning as a heat exchanger comprises two spaced-apart divider wallswhich extend spirally inwards from an inner perimeter of said casingtowards an inner chamber inside said casing. A combustor is installablewithin said chamber having a main exhaust opening formed towards thefirst opening and a plurality of air holes. Since the entire design ofsaid combustor is approximately a can-type shape, the spatialrequirement associated with said engine thus can be significantlyreduced, and eliminates the heat-dissipation issues, greatly increasesfuel efficiency during engine operation.

[0014] Said heat exchanger further comprises a top plate spacing a gapwith the shoulder portion of said casing, said two spaced-apart dividerwalls sealing both ends with the top plate and the bottom plate andforming spirally a compressed air passageway and a turbine exhaust gaspassageway adjacent to each other throughout the heat exchanger. Saidcompressed air passageway of the heat exchanger connects said innerchamber with said gap, said turbine exhaust gas passageway connects themain exhaust opening of said combustor with an exhaust vent formed onthe bottom plate. Because the compressed air passageway and the turbineexhaust gas passageway are spirally formed adjacent to each other, aircoming through the compressed air passageway is preheated along the wayby the exhaust gas vented through the turbine exhaust gas passageway.Thus, the fuel efficiency of a gas turbine engine according to thepresent invention is achieved simply by combusting less fuel withhigher-temperature compressed air.

[0015] Another aforementioned object of the present invention is toimprove on the operational stability of a gas turbine engine by havingsaid compressor rotor and said turbine rotor formed back-to-back on asingle shaft concentrically; wherein, a plurality of compressor rotorblades are perimetrically formed onto said compressor rotor directlybehind said main exhaust opening. Thus, the operational stability of thegas turbine engine according to the present invention is improved byhaving a significantly shorter shaft than that of a conventional gasturbine engine. Another advantage of having a back-to-back rotorarrangement is that the operation life of the shaft bearing is prolongedbecause it is positioned farther away from the combustor than that of aconventional gas turbine engine.

[0016] Other objects, advantages, and novel features of the inventionwill become more apparent from the following detailed description whentaken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0017]FIG. 1 is a schematic diagram of a conventional gas turbine enginerepresented through a sectional view;

[0018]FIG. 2 is a side sectional view of a gas turbine engine accordingto the present invention;

[0019]FIG. 3 is a frontal sectional view A-A of the gas turbine engineshown in FIG. 2.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0020] With reference to FIGS. 2 and 3, there is shown a schematic microgas turbine engine as an example to help illustrate the presentinvention. The gas turbine engine is cylindrical-shaped comprising acasing 1 having a circular shoulder portion 11 which extrudes outwardlyand forms a casing opening 111 to a first end and a bottom plate 12sealing a second end of said casing 1 on the opposite side. An airintake unit 5 having an intake opening 51 is connected to said casingopening 111 to allow more air to enter freely.

[0021] The present invention is characterized by further comprising aSwiss-Roll type recuperator 2 functioning as a heat exchanger havinginternally formed a first divider wall 21 and a spaced-apart seconddivider wall 22, which extend spirally from the outer perimeter of saidcasing 1 towards a cylindrical inner chamber 20 formed approximately tothe center of said casing 1. As shown in FIG. 2, a capital letter “D” islabeled to illustrate the distance between the spaced-apart dividerwalls 21, 22. A combustor 3, preferably a can-type combustor for spatialand heat dissipation reasons, is formed within said inner chamber 20.The combustor 3 further comprises a main exhaust opening 31 formedtowards the first end and a sidewall formed a plurality of air holes 32thereon.

[0022] Said Swiss-Roll type recuperator 2 comprises a first rim 23towards the first end, a second rim 24 towards the second end, and a topplate 230 formed adjacent to the first rim 23; wherein, said top plate230 is positioned approximately perpendicular to said spiral dividerwalls 21, 22. The second rim 24 of said recuperator 2 is sealed by thebottom plate 12 of said casing 1. Thereby, the spaced-apart dividerwalls 21, 22 form spirally a compressed air passageway 25 and a turbineexhaust gas passageway 26 adjacent to each other. The rim 24 of thepresent invention according to this embodiment is sealed by the bottomplate 12 of said casing 1 preferably by, but not limiting to, using acontinuous welding technique.

[0023] The top plate 230 of said Swill-Roll type recuperator 2 spacing agap 201 with the shoulder portion 11 of said casing 1, the compressedair passageway 25 connects said inner chamber 20 with said gap 201, saidturbine exhaust gas passageway 26 connects to the main exhaust opening31 of said combustor 3 with an exhaust vent 121. Wherein, the shape ofthe exhaust vent is substantially semi-annular according to anembodiment of the present invention.

[0024] As shown in FIG. 2, the gas turbine engine of the presentinvention further comprises a turbine engine rotor 4 comprising acoaxial compressor rotor 41 and a turbine rotor 42, a plurality ofcompressor rotor blades 411 perimetrically formed on said compressorrotor 41, and a plurality of turbine rotor blades 421 perimetricallyformed on said turbine rotor 42; wherein, the compressor rotor blades411 are positioned towards said casing opening 111, and the turbinerotor blades 421 are positioned towards said main exhaust opening 31.

[0025] A cold compressed air is initially accumulated after saidcompressor rotor blades 411 draws open air into said intake opening 51by centrifugal force and diffusion effect, and then into said compressedair passageway 25 through said gap 201 spacing by said top plate 230with said shoulder portion 11 of said casing 1. Because the compressedair passageway 25 and the turbine exhaust gas passageway 26 are spirallyformed adjacent to each other, cold compressed air passing through thecompressed air passageway 25 is continuously preheated along the way bythe exhaust gas vented through the turbine exhaust gas passageway 26before it reaches the combustor 3. Thus, the fuel efficiency of a gasturbine engine according to the present invention is achieved simply bycombusting less fuel in the combustor 3 with higher-temperaturecompressed air, also the combustor loading is reduced and stability islifted by increasing the temperature of the compressed air.

[0026] After compressed intake air is combusted with fuel inside saidcombustor 3, high-pressure and high-temperature gas stream is rapidlyforced out of the combustor 3 through said main exhaust opening 31 anddirectly onto said plural turbine rotor blades 421, which drives theturbine rotor 42 into rotation to produce shaft power. Exhaust gas isthen expelled through said exhaust vent 121.

[0027] Thus, the operational stability of the gas turbine engineaccording to the present invention is improved by having a significantlyshorter turbine engine rotor 4 than that of a conventional gas turbineengine. Another advantage of having a back-to-back rotor arrangement isthat the operation life of rotor bearing (not numerated) is prolongedbecause it is positioned farther away from the combustor 3 than that ofa conventional gas turbine engine.

[0028] Although the present invention has been explained in relation toits preferred embodiment, it is to be understood that many otherpossible modifications and variations can be made without departing fromthe spirit and scope of the invention as hereinafter claimed.

What is claimed is:
 1. A gas turbine engine, comprising: acylindrical-shaped casing comprising a circular shoulder portion whichextrudes axially outwards, and forms a casing opening to a first end,and a bottom plate sealing a second end of said casing on the oppositeside; a heat exchanger comprising two spaced-apart divider walls whichextend spirally inwards from an inner perimeter of said casing towardsan inner chamber inside said casing, and a top plate spacing a gap withthe shoulder portion of said casing, said two spaced-apart divider wallssealing both ends with the top plate and the bottom plate and formingspirally a compressed air passageway and a turbine exhaust gaspassageway adjacent to each other throughout the heat exchanger; acombustor installed in the inner chamber of said casing comprising amain exhaust opening formed towards the first end, and a sidewall formeda plurality of air holes thereon; and a turbine engine rotor comprisinga coaxial compressor rotor and a turbine rotor each having a pluralityof blades, wherein the blades of compressor rotor are positioned towardssaid casing opening, and the blades of turbine rotor are positionedtowards said main exhaust opening.
 2. The gas turbine engine as claimedin claim 1, wherein the compressed air passageway of the heat exchangerconnects said inner chamber with said gap; said turbine exhaust gaspassageway connects the main exhaust opening of said combustor with anexhaust vent formed on the bottom plate.
 3. The gas turbine engine asclaimed in claim 2, wherein the exhaust vent is substantiallysemi-annular shape.
 4. The gas turbine engine as claimed in claim 1,wherein the combustor is a can-type combustor.
 5. The gas turbine engineas claimed in claim 1, wherein the gas turbine engine further comprisesan air intake unit having an intake opening adapted for drawing open airinto the casing opening.
 6. The gas turbine engine as claimed in claim1, wherein the heat exchanger is a Swiss-Roll type recuperator.